Range
Black Oystercatchers are resident from the W. Aleutians to east and south along the coast to Morro Bay, California, and on offshore islands to Baja California. Black Oystercatchers spend their entire lives in or near intertidal habitats.

Prey
Intertidal marine invertebrates, particularly bivalves and other mollusks (limpets, whelks, and chitons); also crabs, sea urchins, isopods, and barnacles. Contrary to this species' name, oysters are rarely consumed and are unimportant in their diet.

Size
Sexes are mostly monomorphic in plumage but somewhat dimorphic in size; average height of an adult is 17 in. tall. Black Oystercatchers are a large, heavily built, blackish shorebird, with a straight red bill, flattened laterally. Females have longer, narrower bills and heavier bodies. Legs are a pale flesh color. Immature birds may have a black tip on the bill.

Life Span
Approximately 15 years.

Reproduction
Breeding pairs are established and well-defined. Pairs generally occupy the same feeding and nesting territories year after year, often along low-sloping gravel or rocky shorelines where intertidal prey are abundant. Pairs nest just above the high-tide line and use the intertidal zone to feed themselves and provide for their chicks. Piping (see below) is the most common communicative display given by breeding pairs. Either sex initiates copulation. Paired birds remain together year-round. A small sample of color-banded birds suggests that pairs remain together for years, perhaps for the lives of some birds.

Morphology and Function
Bill morphology is important to capture most prey types. An individual bird moves through its intertidal habitat easily with its long, sturdy legs while visually searching for prey. It locates mussels with valves separated and captures it with quick jabs from its bill. The bird removes the soft parts of the prey with its bill tips. Oystercatchers rarely hammer mussels with their bills to fracture valves. They chip small holes in the shells to reach the prey's adductor muscle. They dislodge limpets and chitons from rocks with quick jabs of their bills aimed at a point where the edge of the shell meets a substrate.

Unique Facts
Pairs often abandon their territories in winter and form flocks. In areas of high mussel density, these flocks often number in the hundreds.

Vocalizations:

Contact Call - Loud, sharp kee note, usually given singly or in series.